Method of producing titanium metal



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2,804,386 METI-Ion OF PRODUCING TITANIUM METAL Edward G. McMackin and John E. =McMillan, Henderson, Gordon W. Miles, Boulder City, and William E. Mooz, Henderson, Nev., assignors to Titanium Metals Corppration of America, New York, N. Y., a corporation of Delaware No Drawing. Application May 31, 1956,

smamassazzs 7 Claims. (CL 7584.5)

Wpractice of the Kroll process, howeverjthe efiiciency'of utilization of the magnesium *reducing metal generally is not high. This efiiciencymay'not exceed 60-75% under ordinary conditions and rarely, if ever, reaches 80% in large commercial size reactors. Apparently, after the reaction has"proceded to a certain extent, an appreciable-1amount .of magnesium is trapped below the 1 titanium sponge" formation and is not available to react withwTiCli' fed from the top. The low efficiency of magnesiumutilizationvresults in'obvious loss of this raw material, and also complicates the subsequent separa- 'tion' of the titaniumi'sporige product fromtheexcess wmagnesium"employed and the magnesium chloride byproduct. Efforts lto feed additional titanium tetrachloride to' the lower portion of the' titaniurn deposit -have generally proved-unsuccessful due to plugging of the titanium'tetrachloride introduction means by formation of-titanium metal in the vicinity of the titanium tetrachloride flow==into the reaction zone. Corrosion of ferrous pipes or other apparatus byreaction with the titanium metal produced has also been a serious problem. It is thereforea principal object of this inventionto xsprovide an improved method for the production'of metallic titanium. An additional' object isto'provide a method for .production'of titanium from titanium tetra -chloride by reduction with a 'reducing 'metal in "which the utilization'efiiciency of the reducing metal is sub- "rstantially-iniproved. A still furtherobject'of this invenl tion is to provide a more efiicient method forproduc- "tion of titaniurnme'tal by reaction of titanium tetrachloride and a reducing metal'with respect'to'utiliiation of the reducing metal and subsequent separation of the rtitanium sponge produced from excessmetallic reducing 1 agent and chloride by-product. Yet another "object of "this invention is toprovide a method forproductionof titanium metal by reaction of titanium tetrachloride with r a reducing metal in which titanium tetrachloride is introduced for contact with said reducing metaltboth on top of the reactionmass'and also from the bottomofthe reaction mass to promote higher utilization of the reduc- -ingmetal employed. These andother*objects of thisinvention will be apparent from the following'complete description thereof. I

Thisinventibnyin its broadest aspects, contemplates Mreduction of titanium'tetrachloride with a reducing'metal in a two-step. process, the reaction being carried outat 2,804,386 "Patented Aug. 27, 1957 substantially atmospheric pressure in a closed reactor under a non-contaminating atmosphere of, for example,

helium or'argon. Titanium tetrachloride is initially introduced at or near the top of a reaction zone and incomprise titanium sponge, metallic magnesium and magnesium chloride by product, an elongated vertical cavity.

The elongated body'may conveniently be in the form of a pipe reaching from above the top of the reactor to a r point near orat the bottom of the reactor. It is a feature and alloy with the ferrous metal pipe is noticeable above of this invention that the external surface of this body is maintained at a'temperature above the freezing point of magnesium chloride, about 710 C. but below about The tendency for metallic titanium to attack 950 C., and the maximum of 920 C. insures a condition under which the pipe will be free from attack. Under these critical conditions the titanium sponge product will not adhere to the pipe surface nor will the pipe itself, which ispreferably composed of a ferrous metal, be

corroded by the reaction products and raw materials,

- andtherebycontaminate the titanium metal being pro- 1 duced. After about 60%to 75 of the tetrachloride has been introduced, the reaction generally slows down, as is-evidenced by a pressure rise in the reaction zone caused by inability of the remaining magnesium metal to absorb and react with the added titanium tetrachloride. Instillation of titanium tetrachloride is, according to this invention, thereupon discontinuedand the remainder of the titanium tetrachloride is introduced into the bottom or lower portion; of the reaction mass to react with the residual magnesium metal which cannot be utilized by titanium tetrachloride being instilled onto the reaction 1 mass from the top. This is accomplished by providing in the cavity maintained during the first step of the process atitanium tetrachloride feed pipe whose open lower extremity extends to -a point near the bottom of the reactor. During introduction of titanium tetrachloride through this bottom feed pipe, titanium metal may form in the vicinity of the pipe open end and partially or wholly obstruct the flow of titanium tetrachloride therefrom. At intervals during the titanium tetrachloride addition, if and when this occurs, the feed pipe is raised sufliciently, generally one to three inches, to provide open unobstructed efiiux of titanium tetrachloride from -the feed. pipe. Titanium tetrachloride is introduced in the second bottom feeding step until a total, including that added in the first step, of up to about 95% of that stoichiometrically required to react withall the magnesium metalpresent has been introduced. It is preferred not to attempt to introduce more than 95% since,-due to "dispersal of the raw materials and inability-to reach-the -last remaining few percent of magnesium metal -the possibility of formation"ofobjectionable titanium 'l'ow'er chlorides I would be increased. A Afterall the titanium tetrachloride has been introduced, the titanium s'pon'ge product is removed from the reactor and separated from the residual small amountof"metallic magnesium and -'magnesium'chloiideby product byconVeIitiOnal methodS.

These may include distillation to remove such'by products in volatile'formor'mayfcomprise leaching with diluteacid to separatethese as soluble compounds. It will be ap- "preciated thatthe substantialreductifon in the amount of residual unreacted magnesiurn considerably-"promotes efiiciency of the"subsequent =purification steps.

The elongated body maintained in the"r'eaction mass during the'top instillatioirof liCl i may be cooled tonne *desired temperature by any suitable' means. Preferably the is formed of iron or steel pipe partially filledwith metallic sodium under an inert gas atmosphere at a pressure of between 3 and '50 mm. of mercury absolute, at room temperature, and sealed. At operating temperature in the reactor the helium pressure will rise to about three times the room temperature pressure 'or between about and 150 mm. 'to provide the required temperato transfer heat and to maintain the desired pipe temperature in the reaction mass. It will be obviousthat the I temperature of the pipe outer wall will always be higher 7 than the controlled temperature inside the pipe and the pressure and corresponding temperature inside the pipe should be such that the outside'of the pipe is normally maintained at a temperature slightly above the freezing point of magnesium chloride andwithin the range 710 to 920 C. A helium or argon atmosphere at a pres sure atoperating temperature of 20 to 50 mm. of mercury absolute above the sodium will result in a controlled temperature of about 750800 C. on the outside of a two inch, one-fourth inch wall mild steel pipe.

' If desired, the elongated body employed to maintain the cavity in'the sponge during the first TiCl4 introduction step may contain the feed pipe employed for bottom feeding TiCLi during the'second TiCl4 introduction step. This may be accomplished by provision of a pair of concentric pipes with the inner pipe open at the bot-' tom for TiCl4 feeding and the annular space between the pipesbeing sealed and containing sodium heat transfer medium. TiCl is fed through the center pipe only "during the secondintroduction, and the whole assembly may be raised periodically to provide unobstructed flow.

During the first TiCl4 introduction step the pipe opi erates at relatively high temperature but during the second step it is adequa ely cooledby passage of liquid TiCLi therethrough. Employment of the integrated assembly involves, therefore, more complex designof sealing means where the pipe passes through the reactor cover since this must operate both at the high temperature involved during the first step and also with'sliding motionwhen the pipe is intermittently raised during the second step; Problems arising from the two conditions may be solved individually by providing a separate sodium 'c-ooled pipe for the first step. which. is 'sealed at the reactor cover by a simple tight fitting metallic collar, or 'fiange, provided with a heat resisting gasket and a second openpipe for the second step which is provided with a sliding seal .of resilient material such as rubber, or a bellows seal, where it passes through the same hole in the cover. At completion of the first TiCLt topyfeed step :the sodium pipe may readily beremovedand the second bottom feed pipe substituted by sliding ittdown into the-cavity left by removal of the first pipe. Contamination'of the titanium metal by atmospheric gases is avoided by providing a substantial outflow of inert gas from the reactor through the temporarily open cover hole duringthe changeover period.

ing just through the cover and a helium feed pipe were also provided in the cover. place and the reactor evacuated and back filled with helium. The reactor was heated to 700 C., the heat shut off, and then titanium tetrachloride introduced through the short top feed pipe at a'rate of 500 lbs. per hour until 3500 lbs. had been introduced. At this point about 68% of the stoichiometric amount to react with the magnesium had been'added and the reaction slowed down. The top TiCl4 was then shut olf. The sodium-containing pipe was then removed and replaced with a'one inch steel pipe open at the bottom and connected 'to the TiCl-z.

feed supply. Helium was introduced into the reactor at 1000 lbs. of liquid TiCLt was then fed through the bottom feed'pipe over a period of 1 /3 hours to bring the total introduced into the reactor to 4600 lbs., or 89.5% of the theoretical amount to react with the 1300 lbs. of magnesium charged. At the end of the reaction the bottom feed pipe was readily removed with its surface clean and uncorroded. Magnesium chloride was then drained from the sponge through a tap hole in the bottom of the reactor, which was then cooled, opened, and

the titanium sponge removed, ground and leached with a dilute HCl solution to remove MgClz and residual magnesium. The titanium metal when melted into an ingot was found to be of good quality, of hardness'125 Brinell and contained 0.05% iron, which is considered it normal content of this impurity. i 1 a 7 Example 2 The operating procedure was essentially the same as that employed in Example 1 except that the sodium cooled,

pipe consisted of a two inch steel pipe with a one inch steel pipe inside it. The central pipe wasopened and l An expanding bellows seal was provided where this. as-

the sealed annular'space between the two pipes contained '3 lbs. of metallic sodium under 30 mm. of mercury absolute pressure of helium at room temperature.

sembly passed through the reactor cover.

Thirty-five hundred pounds of TiCLi was introduced, as

1 beforeby means of the top feed pipe over a period-of seven hours; At the end ofthe third and fifth hours tom of the reaction mass through the central pipe of the magnesium chloride was tapped from the charge and .a total of about 20 lbs. of magnesium was unavoidably removed with the MgClz.

After the 3500 lbs. of TiCL;= had been introduced'the top feed was shut ofl andTiClq. introduced into the bot:

double pipe assembly at a rate of 550 lbs. 'per hour.

After. one-half hour of TiCLi' addition, the flow of TiCl4 through the bottom feed pipe became low and irregular; The pipe was then raised 1 /2 inches to prov1de an open space aroundthebottom of the pipe and flow recommenced at'full rate. This was repeated after The following examples are presented to illustrate embodiments of the processrof this invention; I A

' Example 1 ,A charge of ,1300 lbs. of metallic magnesium was placed "in ajreactor pot around a 'twolinch vertical steel "pipe i sealed at the bottom and top, containing 5 lbs. of metallic. sodium under a pressure of 13 mm. (at room temperature) .of mercury absolute 'of helium. The bottom of, the pipe extended substantially to the bottom of the inside of the reactor. The pipe passed through 'a seal 1 on theireactor cover and the protruding top was provided with a jacket through which air could be passed for cool- ,ing.; A short titanium tetrachloride feed pipe extend- 1% hours when the flow again became obstructed and full normal flow again reobtained.

The amount of TiCl4 introduced in the bottomfeeding step was 1210 lbs., this being' adjusted for the magnesium lostto the reaction during tapping and providing a" total amount of TiCl4." added (both top and bottom) of 93% After introduction of TiCl4 was complete the feed pipe I assembly was readily removed and found tobe clean and uncorroded. The sponge was drained, cooled, ground and leached as in Example 1. -The product'metal was deter mined to be of good quality, of hardness Brinell and contained 0.045% iron. a.

The process of this invention makes possible eflicient operation of the Kroll type'of method for productionof metallictitanium. Provision of the cooled body to maintama cavity in the sponge. is an importantfeature which The cover was sealed in' allows the bottom feed .pipe .to be ,inserted, raised periodically and removed at the end of the run. The tem- 1 body is safely bBlQWuthQIfiIIlPfil'fltllI'C; at whichalloying of Ti and Fe maystart, there is no tendency for the reaction to proceedpn the pipesurface, and:;the advantages of increased efiiciencyi from utilization ,of a substantial amount of magnesium reducing agent which has heretofore been lost mayberealized.

We claim:

1. In a method for production of metallic titanium wherein TiCl4 is added to and reacted with metallic magnesium in a closed reactor under a non-contaminating atmosphere, the steps in combination which comprise; charging metallic magnesium into said reactor, instilling onto the top of said magnesium between about 60% and 75% of the amount of TiCl4 stoichiometrically required to produce metallic titanium by reaction therewith, maintaining during such top addition of TiCli a vertical elongated body, whose outer surface temperature is between about 710 C. and 920 C., in the reaction mass to form a vertical elongated cavity in the titanium sponge formed during such TiCl4 addition, discontinuing instillation of T1014 onto the top of the reaction mass, and introducing additional TiCli into said reactor through a feed pipe disposed in said cavity formed in the titanium sponge and having its lower open extremity near the bottom of said reactor in amount so that the top fed and bottom fed TiCli is between 85 and 95% of that stoichiometrically required to form metallic titanium with the metallic magnesium in the reactor.

2. In a method for production of metallic titanium wherein TiCl4 is added to and reacted with metallic magnesium in a closed reactor under a non-contaminating atmosphere, the steps in combination which comprise; charging metallic magnesium into said reactor, instilling onto the top of said magnesium between about 60% and 75% of the amount of TiCl4 stoichiometrically required to produce metallic titanium by reaction therewith, maintaining during such top addition of TiCli a vertical elongated body, whose outer surface temperature is between about 710 C. and 920 C., in the reaction mass to form a vertical elongated cavity in the titanium sponge formed during such TiCli addition, discontinuing instillation of TiClt onto the top of the reaction mass, introducing additional TiCl4 into said reactor through a feed pipe disposed in said cavity formed in the titanium sponge and having its lower open extremity near the bottom of said reactor in amount so that the total of the top fed and bottom fed TiCl4 is between 85 and 95% of that stoichiometrically required to form metallic titanium with the metallic magnesium in the reactor, and periodically during such bottom addition raising said feed pipe to provide unobstructed efliux of TiCli therefrom.

3. In a method for production of metallic titanium wherein TiCLi is added to and reacted with metallic magnesium in a closed reactor under a non-contaminating atmosphere, the steps in combination which comprise; charging metallic magnesium into said reactor, instilling onto the top of said magnesium between about 60% and 75 of the amount of TiCli stoichiometricaliy required to produce metallic titanium by reaction therewith, maintaining during such top addition of TiCla a vertical elongated body containing a feed pipe, whose outer surface temperature is between about 710 C. and 920 C., in the reaction mass to form a vertical elongated cavity in the titanium sponge formed during such TiCli addition, discontinuing instillation of TiCl4. onto the top of the reaction mass, and introducing additional TiCl4 into said reactor through the feed pipe in said elongated body which has its lower open extremity near the bottom of said reactor in amount so that the total of the top fed and bottom fed TiClq= is between 85% and 95 of that stoichiometrically required to form metallic titanium with the metallic magnesium in the reactor.

4..In a. method forproductiomof metallic titanium .wherein TiCliv is. added. to. andreacted with metallic magnesium in aclosed reactor under. a non-contaminating atmosphere, the stepsincombination which comprise;

charging. metallic magnesium. into said reactor, instilling onto the top of saidamagnesium between; about 60% and"75% of ttheeamount of TiCl4 stoichiometrically required to produce metallic titanium by reaction therewith, maintaining during such top addition of TiCl4- a vertical elongated body, whose outer surface temperature is between about 710 C. and 920 C., in the reaction mass to form a vertical elongated cavity in the titanium sponge formed during such TiCli addition, discontinuing instillation of TiCl4 onto the top of the reaction mass, removing said vertical elongated body and inserting into the cavity in the titanium sponge left by removal of said body a feed pipe having its open lower extremity near the bottom of said reactor and introducing additional TiCli into said reactor through said feed pipe in amount so that the total of the top fed and bottom fed TiCl4 is between and of that stoichiometrically required to form metallic titanium with the metallic magnesium in the reactor.

5. In a method for production of metallic titanium wherein TiCl4 is added to and reacted with metallic magnesium in a closed reactor under a non-contaminating atmosphere, the steps in combination which comprise; charging metallic magnesium into said reactor, instilling onto the top of said magnesium between about 60% and 75% of the amount of TiClq. stoichiometrically required to produce metallic titanium by reaction therewith, maintaining during such top addition of TiCLi a vertical elongated body in the reaction mass in said reactor, cooling said elongated body to maintain its outer surface temperature between about 710 C. and 920 C. thereby to form a vertical elongated cavity in the titanium sponge formed during such TiCLi addition, discontinuing instillation of TlCLI onto the top of the reaction mass, and introducing additional TiClq. into said reactor through a feed pipe disposed in said cavity formed in the titanium sponge and having its lower open extremity near the bottom of said reactor in amount so that the total of the top fed and bottom fed TiCl4 is between 85% and 95 of that stoichiometrically required to form metallic titanium with the metallic magnesium in the reactor.

6. In a method for production of metallic titanium wherein TiCl is added to and reacted with metallic magnesium in a closed reactor under a non-contaminating atmosphere, the steps in combination which comprise; charging metallic magnesium into said reactor, instilling onto the top of said magnesium between about 60% and 75 of the amount of TiCli stoichiometrically required to produce metallic titanium by reaction therewith, maintaining during such top addition of TiCL;= a vertical elongated body in the reaction mass in said. reactor, cooling said elongated body by means of a metallic sodium heat transfer medium to maintain its outer surface temperature between about 710 C. and 920 C. thereby to form a vertical elongated cavity in the titanium sponge formed during such TiCl4 addition, discontinuing instillation of TiCli onto the top of the metallic magnesium, and introducing additional TiCl4 into said reactor through a feed pipe disposed in said cavity formed in the titanium sponge and having its lower open extremity near the bottom of said reactor in amount so that the total of the top fed and bottom fed TiCl4 is between 85% and 95% of that stoichiometrically required to form metallic titanium with the metallic magnesium in the reactor.

7. In a method for production of metallic titanium wherein TiCli is added to and reacted with metallic magnesium in a closed reactor under a non-contaminating atmosphere, the steps in combination which comprise; charging metallic magnesium into said reactor, instilling and 75% of the amount of TiCl4 stoichiometrically required to produce metallic tianiurn by reaction therewith,

. maintaining during such top addition of TiCl4 a vertical elongated body in the reaction mass in said reactor, cool-Z ing said elongated body by means of a metallic sodium 'heat transfer agent maintained under an atmosphere of inert gas at a pressure of between 10 mm. and 150 mm. of mercury absolute to maintain its outer surface temperature between about 710 C. and 920 C. thereby to form a vertical elongated cavity in the titanium sponge formedduring such TiCl4 addition, discontinuing instillationrof TiC14 onto the top of the metallic magnesium, and introducing additional TiCl4 into said reactor through a feed pipe disposed in said cavity formed in the titanium sponge and having its lower open extremity near the bottom of said reactor in amount so that the totalvof the top fed and bottom fed TiCh is between 85% and 95% of that stoichiometrically required to form metallic titanium 'with the metallic'magnesium in the reactor.

No references cited. 

1. IN A METHOD FOR PRODUCTION OF METALLIC TITANIUM WHEREIN TICL4 IS ADDED TO AND REACTED WITH METALLIC MAGNESIUM IN A CLOSED REACTOR UNDER A NON-CONTAMINATING ATMOSPHERE, THE STEPS IN CONBINATION WHICH COMPRISE; CHARGING METALLIC MAGNESIUM INTO SAID REACTOR, INSTILLING ONTO THE TOP OF SAID MAGNESIUM BETWEEN ABOUT 60% AND 75% OF THE AMOUNT OF TICL4 STOICHIOMETRICALLY REQUIRED TO PRODUCE METALLIC TITANIUM BY REACTION THEREWITH, MANTAINING DURING SUCH TOP ADDITION OF TICL4 A VERTICAL ELONGATED BODY, WHOSE OUTER SURFACE TEMPERATURE IS BETWEEN ABOUT 710*C. AND 920*C., IN THE REACTION MASS TO FORM A VERTICAL ELONGATED CAVITY IN THE TITANIUM SPONGE FORMED DURING SUCH TICL4 ADDITION, DISCONTINUING INSTILLATION OF TICL4 ONTO THE TOP OF THE REACTION MASS, AND INTRODUCING ADDITIONAL TICL4 INTO SAID REACTOR THROUGH A FEED PIPE DISPOSED IN SAID CAVITY FORMED IN THE TITANIUM SPONGE AND HAVING ITS LOWER OPEN EXTREMITY NEAR THE BOTTOM OF SAID REACTOR IN AMOUNT SO THAT THE TOP FED AND BOTTOM FED TICL4 IS BETWEEN 85% AND 95% OF THAT STOICHIOMETRICALLY REQUIRED TO FORM METALLIC TITANIUM WITH THE METALLIC MAGNESIUM IN THE REACTOR. 